Tet-Mediated Formation of 5-Hydroxymethylcytosine in RNA.

Oxidation of 5-methyl cytosine in DNA by ten-eleven translocation (Tet) family of enzymes has been demonstrated to play a significant role in epigenetic regulation in mammals. We found that Tet enzymes also possess the activity of catalyzing the formation of 5- hydroxymethylcytidine (5-hmrC) in RNA in vitro. In addition, the catalytic domains of all three Tet enzymes as well as full-length Tet3 could induce the formation of 5- hmrC in human cells. Moreover, 5-hmrC was present at appreciable levels (~1 per 5000 5-methylcytidine) in RNA of mammalian cells and tissues. Our results suggest the involvement of this oxidation in RNA biology. [ABSTRACT FROM AUTHOR]